What is OJ287?

OJ287 was first detected as a radio source in the Ohio surveys in 1968. It was soon identified with a 15th magnitude compact blue object like a typical quasar. Unlike a normal quasar, the optical spectrum was found to be featureless, but very weak, variable emission lines have since been detected, with a red shift of z=0.306. OJ287 was classified first as a BL Lac Object and, later, as a blazar – a quasar with extreme variability.